This invention relates in general to drive train assemblies for transferring rotational power from an engine to an axle assembly in a vehicle. In particular, this invention relates to an improved structure for a slip yoke assembly adapted for use in such a vehicle drive train assembly.
In most land vehicles in use today, a drive train assembly is provided for transmitting rotational power from an output shaft of an engine/transmission assembly to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. To accomplish this, a typical vehicular drive train assembly includes a hollow cylindrical driveshaft tube. A first universal joint is connected between the output shaft of the engine/transmission assembly and a first end of the driveshaft tube, while a second universal joint is connected between a second end of the driveshaft tube and the input shaft of the axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of angular misalignment between the rotational axes of these three shafts.
Not only must the drive train assembly accommodate a limited amount of angular misalignment between the engine/transmission assembly and the axle assembly, but it must also typically accommodate a limited amount of axial movement therebetween. A small amount of such relative axial movement frequently occurs when the vehicle is operated. To address this, it is known to provide one or more slip yoke assemblies in the drive train assembly. A typical slip yoke assembly includes first and second splined members which are connected to respective components of the drive train assembly. The splined members provide a rotational driving connection between the components of the drive train assembly, while permitting a limited amount of axial misalignment therebetween. In some instances, the first splined member may be provided on the end of a yoke member connected to a universal joint assembly, while the second splined member may be connected to a driveshaft section of the drive train assembly.
As is well known in the art, most slip yoke assemblies are provided with sealing structures to prevent the entry of dirt, water, and other contaminants into the region where the splined members engage one another. Such contaminants can adversely affect the operation of the slip yoke assembly and cause premature failure thereof. A number of sealing structures are known in the art for use with conventional slip yoke assemblies. Both exterior and interior sealing structures must typically be provided to fully protect the region where the splined members engage one another. Exterior sealing structures are disposed on the outer surface of the slip yoke assembly and prevent contaminants from entering into this region from the exterior environment. For example, it is well known to provide an annular seal assembly on one of the splined members which slidably engages the other of the splined members. Typically, however, the surface which is slidably engaged by such an annular seal assembly must be carefully machined to provide a smooth sliding surface. Interior sealing structures are disposed within the slip yoke assembly and prevent contaminants from entering into this region through the hollow yokes or driveshaft sections connected to the splined members. For example, it is known to provide an internal plug to close the interior of a hollow yoke or driveshaft section. Typically, however, the plug must include a retaining mechanism of some sort to prevent it from becoming dislodged during use. These additional structures result in higher manufacturing and assembly costs for the slip yoke assembly. Thus, it would be desirable to provide an improved structure for a slip yoke assembly which is relatively simple and inexpensive in construction and assembly.